images: add Ubuntu 20.04 image

[francesconicoletta]

This should add an Ubuntu 20.04 LTS image, the packages are pretty much the same as Fedora, plus libcap2-bin, needed to fix "/bin/bash not found in container".

[softwarefactory-project-zuul]

Build failed.

• unit-test : SUCCESS in 3m 17s
• system-test-fedora-33 : FAILURE in 10m 25s
• system-test-fedora-34 : SUCCESS in 10m 18s
• system-test-fedora-rawhide : SUCCESS in 13m 55s

[JeremiahSecrist]

I have noticed with all of these images that none of theme seem to work with apt / apt-get. The package manager is completely missing on every single image I have tried.

[Jmennius]

I have noticed with all of these images that none of theme seem to work with apt / apt-get. The package manager is completely missing on every single image I have tried.

Did you try images from #483?

[andrewshadura]

See also #298, #371, #742.

[debarshiray]

#483 supersedes this.

[debarshiray]

Closing.